1. Technical Field
The present invention relates to an image forming apparatus, a printer driver, a program and a recording medium which can satisfy both conflicting requests from a user that a processing time for image forming is short and that an image with high quality is obtained.
2. Background Art
It has been conventionally known that printout characteristics such as density are changed due to a change in environments such as temperature and humidity in a setting location of an image forming apparatus including a copier, a printer, a facsimile machine or a combination of the machines and a change over time in the status of each component of the apparatus. In a color copier, for example, the amount of toner adhered to recording paper is changed when the temperature, humidity or the like in an atmosphere of its setting location is changed, and thus its output characteristics deviate from the characteristics as they should be intrinsically. In addition, the temperature in each component of the apparatus is raised when image forming processing is performed in succession for a long time, whereby a deviation can be also caused in the output characteristics.
In order to compensate for such a change in output characteristics involved in a disturbance, an adjustment (hereinafter referred to as a calibration) of the output characteristics is generally made in the image forming apparatus. It is known as a calibration, for example, to form a patch image for adjusting the output characteristics on an intermediate transfer member, read its toner density, feed back its result and adjust the developing bias value of a developing machine.
The calibration plays an important role in maintaining image quality above a certain level in the apparatus. On the other hand, processing of the calibration takes a relatively long time, for example, several tens of seconds, which causes a disadvantage that the apparatus is not available during that time.
As an approach to eliminate the disadvantage, Japanese Published Unexamined Patent Application No. 2006-130779 discloses art wherein a calibration is not conducted until the cumulative number of copies exceeds a predetermined value when a copy job is performed in succession, thereby attempting to suppress sudden performance of the calibration during the job or between each job and interruption of copying by the calibration as much as possible, for example.
However, the aforementioned prior art uniformly processes whether to perform the calibration in a case where a copy job is carried out in succession, based on whether the cumulative number of copies exceeds a predetermined value in the job. Consequently, conflicting requests from a user that a processing time for image forming is short and that an image with high quality is obtained cannot both be satisfied.